The Value Of Structural Imaging In The Prognosis Of Patients With Idiopathic Normal Pressure Hydrocephalus After Shunt Surgery

Objective: Neurostructural changes in idiopathic normal pressure hydrocephalus(iNPH)are characteristic,but their role in predicting the outcome of shunt surgery for iNPH remains controversial.This study used two semi quantitative imaging scales with different standards to explore the potential relationship between imaging characteristics of neural structures of iNPH and the efficacy of shunt surgery and clinical symptoms related to iNPH.Methods: A total of 47 patients with iNPH who underwent shunting surgery at our institution between 2018 and 2020 were included in this study.The modified Rankin Scale(m RS)and iNPH grading scale(iNPHGS)were used to assess clinical symptoms or daily living abilities before and after shunt surgery.A preoperative cranial magnetic resonance imaging(MRI)was assessed using the disproportionately enlarged subarachnoid space hydrocephalus(DESH)score and the idiopathic normal pressure hydrocephalus radiation scale(iNPH Radscale),which measures and assesses all morphometric imaging parameters included in both scales,including the lateral ventriculomegaly index(Evans’ index,EI),widening of the sylvian fissures,narrow sulci,angulation of the callosal angle(CA),focally dilated sulci,width of the temporal horns of the lateral ventricles,periventricular hyperintensities(PVH).Patients were followed up one year after surgery.The primary end point was the change in m RS scores one year after surgery,and the secondary end point was the change in iNPHGS scores one year after surgery.A decrease of 1 or more in both scores was defined as postoperative improvement.All patients were divided into an improvement group and a non-improvement group,and the preoperative clinical symptoms and structural imaging characteristics of the improvement group and the non-improvement group were retrospectively compared.Results: One year after shunt,the improvement rates for primary and secondary outcome indicators were 59.6% and 61.7%,respectively.There was no significant correlation between preoperative age,course of disease,m RS score,and iNPHGS score of patients and postoperative improvement;There were no significant differences between the improved and non-improved groups in preoperative DESH scores,iNPH Radscale scores,and individual EI,CA,PVH,widening of the sylvian fissures,narrow sulci,focally dilated sulci,and the width of the temporal horns of the lateral ventricles.Only EI and temporal angle width had a significant but low correlation with the severity of gait disorders(correlation coefficient R<0.5).Conclusions: Structural imaging has limited value in evaluating the efficacy of iNPH shunt one year after surgery,and should not be used solely as a basis for screening shunt candidates.iNPH has characteristic clinical symptoms and imaging findings,but the correlation between the two is not significant.Only gait disorders are associated with EI and the width of the temporal horns,but the correlation is low.